A preliminary assessment of the palate and tongue for detecting organophosphorus and carbamate pesticide exposure in the degraded carcasses of vultures and other animals

Abstract

In many regions of the world, organophosphorus (OP) and carbamate (CM) pesticides are used to poison wildlife thought to be competing with human activities (e.g. hunting). Vultures may be secondarily poisoned or directly targeted, e.g. for muti or traditional medicine. Some OPs and CMs are so acutely toxic that animals will die with poisoned material still in their mouths - un-swallowed, before traces may have spread to other parts of the body. Even when death is more prolonged, the tissues in which residues have accumulated may deteriorate before the carcass is discovered, minimizing the chances of recovering viable samples for toxicological analyses that would conclusively identify poisoning as the cause of death. With all these factors in mind, we investigated the feasibility of detecting OP and CM pesticides in the oral cavity, with emphasis on the tongue and palate. A total of 60 degraded carcasses (n = 28 avian and 32 mammalian) recovered from various scenes of wildlife crime in Andalucía, southern Spain, where poisoning was suspected, were submitted to the Center for Analysis and Diagnosis of Wildlife in Málaga for necropsy and toxicological analyses. Of these, 20 and 24 avian and mammalian tongues, respectively, could be recovered for analysis. Separately, the palate from one degraded Cinereous Vulture Aegypius monachus carcass was also opportunistically retrieved and analyzed following an incident of vulture mass-mortality in which nine Griffon Vultures Gyps fulvus also perished. Residues or presence of OPs and CMs were detected in one avian tongue (analyzed with food from the mouth) and four mammalian tongues. Our findings suggest avian tongues alone are not optimal, but canid tongues and those of larger mammals may lend themselves well to analysis. Detection of the OP chlorfenvinphos (3.39 mg/kg) in the Cinereous Vulture palate (the only part of the carcass in which residues were detected) indicates this is a promising sample. To our knowledge, this represents the first time that OP and CM pesticides have been detected in tongue and palate samples. We recommend further exploration of oral cavity samples, especially within the context of the risk that residues therein may pose to human health.

See supplementary file attached